ocaml: phase 1 sequence operator ; (+10 tests, 123 total)

Two-phase grammar: parse-expr-no-seq (prior entry) + parse-expr wraps
it with ;-chaining. List bodies keep parse-expr-no-seq so ; remains a
separator inside [...]. Match clause bodies use the seq variant and stop
at | — real OCaml semantics. Trailing ; before end/)/|/in/then/else/eof
permitted.

lib/ocaml/test.sh

@@ -300,6 +300,28 @@ cat > "$TMPFILE" << 'EPOCHS'
 (epoch 308)
 (eval "(ocaml-parse \"match x with | () -> 0\")")
 
+;; ── Sequences (;) ──────────────────────────────────────────────
+(epoch 320)
+(eval "(ocaml-parse \"1; 2\")")
+(epoch 321)
+(eval "(ocaml-parse \"1; 2; 3\")")
+(epoch 322)
+(eval "(ocaml-parse \"(1; 2)\")")
+(epoch 323)
+(eval "(ocaml-parse \"begin a; b; c end\")")
+(epoch 324)
+(eval "(ocaml-parse \"let x = 1 in x; x\")")
+(epoch 325)
+(eval "(ocaml-parse \"if c then (a; b) else c\")")
+(epoch 326)
+(eval "(ocaml-parse \"[1; 2; 3]\")")
+(epoch 327)
+(eval "(ocaml-parse \"1; 2;\")")
+(epoch 328)
+(eval "(ocaml-parse \"begin a; end\")")
+(epoch 329)
+(eval "(ocaml-parse \"match x with | _ -> a; b\")")
+
 EPOCHS
 
 OUTPUT=$(timeout 60 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
@@ -476,6 +498,18 @@ check 306 "match ctor with tuple arg"    '("pcon" "Pair" ("pvar" "a") ("pvar" "b
 check 307 "match string literal"         '("plit" ("string" "hi"))'
 check 308 "match unit pattern"           '("plit" ("unit"))'
 
+# ── Sequences ───────────────────────────────────────────────────
+check 320 "seq 1;2"                      '("seq" ("int" 1) ("int" 2))'
+check 321 "seq 1;2;3"                    '("seq" ("int" 1) ("int" 2) ("int" 3))'
+check 322 "seq in parens"                '("seq" ("int" 1) ("int" 2))'
+check 323 "seq in begin/end"             '("seq" ("var" "a") ("var" "b") ("var" "c"))'
+check 324 "let body absorbs seq"         '("let" "x" () ("int" 1) ("seq" ("var" "x") ("var" "x")))'
+check 325 "if-branch parens for seq"     '("if" ("var" "c") ("seq" ("var" "a") ("var" "b"))'
+check 326 "list ; is separator"          '("list" ("int" 1) ("int" 2) ("int" 3))'
+check 327 "trailing ; OK"                '("seq" ("int" 1) ("int" 2))'
+check 328 "begin a; end singleton seq"   '("seq" ("var" "a"))'
+check 329 "match clause body absorbs ;"  '("case" ("pwild") ("seq" ("var" "a") ("var" "b")))'
+
 TOTAL=$((PASS + FAIL))
 if [ $FAIL -eq 0 ]; then
   echo "ok $PASS/$TOTAL OCaml-on-SX tests passed"